I got an electrical problem

641Dave · Jul 27, 2012

I fired my 641 last night. Had some trouble after my rewire job.

I got it started, but noticed the wire to the new alt was loose. The one going to the main source. I tightened it and then nothing. Took it off and I had power to the volt meter again and she fired right up.

Here is what I did to my 1958 601. I have the diodes in there on the wire to the alt but didn't put them in the illustration.

I'm not sure whats going on.

BTW, new 12 volt 12si alt. Negative ground.

641Dave · Jul 27, 2012

Here's what I went by minus the amp meter.

jackinok · Jul 27, 2012

i would check the alternator first to see if youve got a bad one.

641Dave · Jul 27, 2012

I went out this morning to draw my diagram. I had the wire off the alt and put the key in and everything lit up right.

As soon as I touched the main wire to the alt, everything went dead. I think you maybe right and maybe I have a short in the alt. ?

I'll take it back up and have it checked.

....or a short in the wire to the terminal. hmmmm.

Anyway, does my diagram look alright? I just wasn't sure since I didn't have an ampmeter or light hooked up and if that was the problem. My hot wire to the alt is wired straight into the junction box.

Anonymous-0 · Jul 27, 2012

Remember, that alternators don't like having the wires removed
from the battery, eats diodes. If you have connection problems, it
is best to have the key off, when working on them.

old · Jul 27, 2012

#1 NEVER ever remove the battery cable with the engine running to check an alternator. 2 things can/will happen #1 the alternator sees a dead battery so goes to max charge which in turn burns out the V.R. diodes in it then it in turn puts out AC current at 90 plus volts and 35 plus amps which if you get between the cable and ground you in turn send you to your grave. From what you have said you need to take that alternator in and have it checked bet you let the smoke out of it. Also the #2 wire off the plug can go right to the big post of the alternator instead of running a long wire to where you did and that in turn saves $$ and problem down the rode

jackinok · Jul 27, 2012

yes you can get a bad one ocasionally. bad thing is often parts store wont take them back since they are electrical.

641Dave · Jul 30, 2012

Alt checked out okay.

Maybe this is the problem. I bought two diodes from radio shack # 1N5402 and since there was two in the package, I wire both of them in. Is that the problem, having two diodes wired in???

Here is the direction I have the diodes. Alt to the left, terminal block to the right. Is that right?

Is it possible I don't have a good ground on the alt? Should I run a ground wire?

Royse · Jul 30, 2012

If I'm reading this right, your voltage at the voltmeter drops
to zero when you hook up the wire to the large terminal on the
back of the alternator?
That would be a dead short (or something close to it) and I'm
surprised it doesn't arc and spark all over.
As far as the diodes go, they are not in that big wire, the diode
goes in the wire from the key switch.
Cathode to the alternator would be correct, but you only need one.
I installed one tonight. Different part number, but from what I can tell
mine was 6A rated as opposed to 3a.
I can't tell for sure in your diagram which post from the alternator
you have hooked to where on the other end. That may shed some light?
IIRC, with a 4 wire solenoid, the purpose of the fourth wire was to
bypass the resistor at start up in an attempt to give you hotter spark
while cranking.
Assuming that's correct, that wire should go to the left of the resistor
in your drawing. That would not cause this problem though.
You might try googling "JMOR wiring diagrams" and comparing his pictograms to what you have.
They're nicely done and easy to visualize while comparing to what
you have.
HTH

Gerry....WI · Jul 30, 2012

One diode is all that is necessary. Your blocking the circuit.

641Dave · Jul 31, 2012

(quoted from post at 05:18:09 07/31/12) One diode is all that is necessary. Your blocking the circuit.

I didn't know that would cause a problems. I figured what one would do, two would do better. Thanks. I'll take the diode off tonight and hopefully I'll finally have a tractor again.

641Dave · Aug 3, 2012

I removed one of the diodes and added a ground wire to the back of the alt.

Fixed it.

Thanks fellas!

I got an electrical problem

641Dave

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old

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Gerry....WI

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